It's been half a year since Yusuke's father left home with another woman. Kana has always acted tough in front of his son, but he knows his mother is still grieving. Seeing the lonely look on his mother's face made Yusuke feel heartbroken, but he didn't know how to make his mother happy again. One day, Yusuke accidentally witnessed his mother masturbating. From that moment on, he determined to replace his father's position and bring happiness to his mother. At first Kana was also surprised and confused. But when she realized her son's care and concern for her, she gradually accepted this.